using the retardation factor, estimate the time for DDT to reach a well 2 km (1.24 miles)/, away if the pore-water velocity = 0.1 m/day, the soil bulk density = 1.2 g/m^3, n= 0.45, and the average soil organic carbon content = 0.01%. assume that soil organic carbon is the primary sorbent and that degredation and dispersion are negligible.